Construction machinery

ABSTRACT

A construction machine of the present invention is provided, in a compartment formed by a cover, with an engine, a centrifugal fan, and a heat exchanger for exchanging heat between cooling air blown by the centrifugal fan and a specified medium, wherein the centrifugal fan and the heat exchanger are arranged further upstream than the engine with respect to flow of cooling air, so that cooling air sucked in by the centrifugal fan is led to the engine after passing through the heat exchanger.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a construction machine having acooling fan, a radiator, and an oil cooler etc.

[0003] 2. Description of the Related Art

[0004] Generally, a swiveling type construction machine such as ahydraulic excavator is known as a construction machine. This hydraulicexcavator is made up of a lower traveling body capable ofself-propulsion, and an upper swiveling body mounted upon theundercarriage. A working unit capable of moving up and down for carryingout land excavation etc. is provided on the front of the upper swivelingbody.

[0005] The upper swiveling body comprises a swiveling frame forming thestructure body, an engine mounted on the swiveling frame, a hydraulicpump driven by the engine, a hydraulic oil tank for storing hydraulicoil mounted on the swiveling frame, heat exchangers such as a radiatorfor cooling engine coolant and an oil cooler for cooling the hydraulicoil, and a cooling fan for feeding cooling air towards the heatexchangers.

[0006] In recent years it has become usual for construction machinessuch as hydraulic excavators to carry out operations at constructionsites within towns and streets etc., and there has been a demand for lownoise operation. A hydraulic excavator using a sirocco fan (multi-bladefan) that runs comparatively silently as a cooling fan to meet thisrequirement is disclosed, for example, in Utility Model Laid-open No.Hei. 6-1725 and Japanese Patent Laid-open No. Hei. 7-83054. With thehydraulic excavators in these publications, cooling air that has beensucked in by the sirocco fan is blown out to heat exchangers such as aradiator and an oil cooler arranged above the sirocco fan, and heat isexchanged between the cooling air and the cooling water inside theradiator, and the hydraulic oil inside the oil cooler.

[0007] With the hydraulic excavators described in the abovepublications, cooling air taken into an engine compartment is led to theheat exchangers by way of the outside of the engine. Thus, cooling airof comparatively high-temperature passes through the heat exchanger, andthis is not preferable from the point of view of cooling efficiency. Inorder to achieve a specified heat balance, if the cooling efficiency islow, the rotational speed of the cooling fan must be increased or theheat exchangers must be made larger in size. However, if the rotationalspeed of the cooling fan is increased, it becomes noisier. Also, if theheat exchangers are made larger, the rear end radius of a machine bodybecomes larger and operation at narrow and limited construction sitessuch as are found within towns and streets becomes difficult.

[0008] The hydraulic excavators of the above publications have the heatexchangers mounted at an upper side of the sirocco fan, therefore thesirocco fan and the motor etc. become located at a position below theheat exchangers and become hidden from view. As a result, when carryingout inspection and maintenance of the sirocco fan and motor, such ascleaning and repair operations, there is a problem of poor operabilitybecause it is difficult for an operator's hands to reach the sirocco fanand motor, as well as the difficulty for visual confirmation.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to provide a constructionmachine for obtaining improved cooling efficiency together with reducednoise.

[0010] In order to achieve the above described object, a constructionmachine of the present invention comprises, in a compartment formed by acover, an engine, a centrifugal fan, and a heat exchanger for exchangingheat between cooling air blown by the centrifugal fan and a specifiedmedium, wherein the centrifugal fan and the heat exchanger are arrangedon the upstream side of the engine with respect to flow of cooling air,so that cooling air sucked in by the centrifugal fan is led toward theengine after passing through the heat exchanger.

[0011] In this way, together with being able to reduce noise, lowtemperature air is blown onto the heat exchanger and cooling efficiencyis improved.

[0012] It is preferable that the intake side of the centrifugal fan ispartitioned off from the exhaust side of the heat exchanger and theengine. Together with providing a driver's seat offset in the widthwisedirection of the machine, it is possible to provide the engine behindthe driver's seat and to arrange the centrifugal fan offset to theopposite side in the widthwise direction of the machine.

[0013] The centrifugal fan may be arranged above the heat exchanger witha duct for guiding cooling air from the centrifugal fan to the heatexchanger.

[0014] In this way, it is possible to simply carry out inspectionoperations and maintenance operations for the sirocco fan etc, and toimprove operability.

[0015] It is preferable to arrange the centrifugal fan at an upper partof the compartment and to provide an intake port for cooling air at anupper part of the cover.

[0016] An axis of the centrifugal fan may be provided in a widthwisedirection of the machine. In this case, it is preferable to locate anexhaust port for the cooling air below the engine.

[0017] It is possible to arrange the hydraulic pump driven by the engineand at least one of the hydraulic fluid reservoir for storing hydraulicfluid and a control valve for controlling flow of hydraulic fluid fromthe hydraulic pump to an actuator, at a centrifugal fan side of thecompartment. It is also possible to provide a duct for guiding coolingair from the centrifugal fan to the heat exchanger, and to arrange theduct adjacent to the hydraulic fluid reservoir.

[0018] It is acceptable to arrange the heat exchanger behind thedriver's seat, and to arrange the engine to the side of the heatexchanger in a widthwise direction of the machine. In this case, it ispreferable to arrange a rotation shaft of the centrifugal fansubstantially in a horizontal direction and to arrange the heatexchanger above the centrifugal fan. Alternatively, the rotation shaftof the centrifugal fan may be arranged substantially in a verticaldirection and the heat exchanger may be arranged to the side of thecentrifugal fan.

[0019] It is also possible to arrange the heat exchanger substantiallyvertically with respect to the flow of cooling air blown from thecentrifugal fan. The heat exchanger may comprise an oil cooler and aradiator, arrange the radiator in an outlet of a duct passage made of aduct, and arrange the oil cooler substantially vertically with respectto the duct passage at a specified location of a duct passage having asmaller passage area than the outlet of the duct passage.

[0020] It is also acceptable to provide a straightening vane directlydownstream of the heat exchanger with respect to the flow of coolingair, and to change the flow of cooling air that has passed through theheat exchanger to a specified direction.

[0021] The present invention is preferably applied to a mini excavator.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a front elevation of a hydraulic excavator to which afirst embodiment of the present invention is applied.

[0023]FIG. 2 is a plan view showing the appearance of an upper swivelingbody with an external cover and driver's seat etc. removed.

[0024]FIG. 3 is a front elevation view showing the appearance of theupper swiveling body with a counter weight, the external cover and thedriver's seat etc. removed.

[0025]FIG. 4 is a perspective view showing an enlargement of theappearance of the upper swiveling body with a counter weight, theexternal cover and the driver's seat etc. removed.

[0026]FIG. 5 is a front elevation showing an enlargement of a hydraulicfluid reservoir, a cooling air duct, a sirocco fan, a radiator and anoil cooler.

[0027]FIG. 6 is a cross sectional drawing along line VI-VI in FIG. 5.

[0028]FIG. 7 is a front elevation showing a hydraulic fluid reservoir,cooling air duct, sirocco fan and heat radiating fan of a secondembodiment of the present invention, together with a radiator and oilcooler.

[0029]FIG. 8 is a cross sectional drawing along line VIII-VIII in FIG.7.

[0030]FIG. 9 is a front elevation showing a cooling air duct and siroccofan of a third embodiment of the present invention, together with ahydraulic fluid reservoir, radiator and oil cooler.

[0031]FIG. 10 is a front elevation showing a hydraulic excavator towhich a fourth embodiment of the present invention is applied.

[0032]FIG. 11 is a plan view showing a hydraulic excavator to which thefourth embodiment of the present invention is applied.

[0033]FIG. 12 is a cross sectional drawing showing arrangement of anengine unit of the fourth embodiment of the present invention.

[0034]FIG. 13 is a cross sectional view along line XIII-XIII in FIG. 12.

[0035]FIG. 14 is a cross sectional view along line XIV-XIV in FIG. 12.

[0036]FIG. 15 is an external perspective view showing a duct of thefourth embodiment of the present invention.

[0037]FIG. 16 is a drawing showing a modification of FIG. 12.

[0038]FIG. 17 is a cross sectional drawing showing arrangement of anengine unit of a fifth embodiment of the present invention.

[0039]FIG. 18 is a cross sectional drawing showing arrangement of anengine unit of a sixth embodiment of the present invention.

[0040]FIG. 19 is a cross sectional view along line XIX-XIX in FIG. 18.

[0041]FIG. 20 is a cross sectional drawing showing arrangement of anengine unit of a seventh embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] A hydraulic excavator, particularly a mini excavator capable ofsmall turns, will be described in detail in the following as an exampleof a construction machine of an embodiment of the present invention,with reference to the attached drawings. A mini excavator is a hydraulicexcavator having a machine weight of, for example, less than 6 tons. Inthe following, as shown in the attached drawings, the longitudinal andlateral directions of the hydraulic excavator are defined, andarrangement of respective parts will be described based on thisdefinition.

[0043] First Embodiment

[0044] A first embodiment of a construction machine of the presentinvention will now be described with reference to FIG. 1-FIG. 6.

[0045] The hydraulic excavator of this embodiment has a lower travelingbody 1 and an upper swiveling body 2 mounted on the undercarriage 1 soas to be capable of swiveling, and a boom 3 for carrying out excavationis provided at a front side of the upper swiveling body 2.

[0046] As shown in FIG. 1 and FIG. 2, the upper swiveling body 2 mainlycomprises a swiveling frame 4, which will be described later, a driver'sseat 7, an engine 10, a hydraulic pump 11, a control valve unit 12, ahydraulic fluid reservoir 13, a cooling air duct 14, a sirocco fan 16, aradiator 20 and an oil cooler 21, etc. The upper swiveling body 2 has asubstantially circular shape overall when viewed from above.

[0047] As shown in FIG. 3 and FIG. 4, the swiveling frame 4 constitutinga support structure for the turntable section 2 is mainly made up of aflat plate-shaped base plate 4A extending to the front and rear, a lefterected plate 4B erected to the left side of the base plate 4A andinclined to the right side as extending from the rear to the front, aright erected plate 4C erected to the right side of the base plate 4A,extending to the front and rear, and an upper plate 4D fixed to frontupper sides of each of the erected plates 4B and 4C. A boom 3 is thenattached to front end sections of the base plate 4A and upper plate 4Dconstituting the swiveling frame 4.

[0048] Beams 4E and 4F are provided on the right side of the swivelingframe 4, and the control valve unit 12 and the hydraulic fluid reservoir13, which will be described later, are mounted on the beams 4E and 4F. Amotor bracket 4G extending to an upper side from the vicinity of theright side plate 4C is provided on a rear side of the swiveling frame 4,and a drive motor 19 for the sirocco fan 16, which will be describedlater, is attached to an upper part of the motor bracket 4G.

[0049] A breather 4H (shown in FIG. 2 and FIG. 3) is formed in the baseplate 4A of the swiveling frame 4, at a lower side of the engine 10,which will be described later. The breather 4H is a slit shape orcovered by a net, and cooling water that passes through the radiator 20,described later, and becomes hot is discharged to the outside throughthis breather 4H.

[0050] A counterweight 5 for providing a weight balance for the boom 3is attached to a rear end section of the swiveling frame 4, thecounterweight 5 being formed in an arc shape corresponding to theturning radius.

[0051] An external cover 6 is provided so as to cover the outer side ofthe swiveling frame 4. The external cover 6 is mainly comprised of aright cover 6A, positioned at an upper right side of the swiveling frame4, for covering the control valve unit 12, described later, thehydraulic fluid reservoirs 13, the sirocco fan 16 and the radiator 20etc., a left cover (not shown in the drawings), positioned at an upperleft side of the swiveling frame 4, for covering the engine 10,described later, a rear cover 6B, positioned at an upper side of thecounterweight 5, for covering the engine 10 etc. from an upper side, anda skirt cover 6C for covering the periphery of the swiveling frame 4. Anengine chamber 100 is formed by these covers 6A, 6B and 6C.

[0052] The right cover 6A and the left cover 6B are made capable ofbeing opened and closed in order to carry out inspection operations andmaintenance operations of respective components covered by these covers6A and 6B. A breather 6D as shown in FIG. 1 is provided in the rightcover 6A. The breather 6D is for cooling air to flow for supply to thesirocco fan 16, to be described later, and opens to a positioncorresponding to an intake side of the sirocco fan 16.

[0053] The driver's seat 7 is provided at a front side of the rear cover6B. The driver's seat 7 is provided to the left in the lateral directionof the swiveling frame 4. A travel lever 8 for causing the lowertraveling body 1 to travel is provided at a front side of the driver'sseat 7, and operating levers 9 for operating the boom 3 are provided onboth left and right sides of the driver's seat 7.

[0054] Further to the rear left side of the swiveling frame 4, theengine 10 is provided on the front side of the counterweight 5. Theengine 10 is transversely mounted extending in the lateral direction.The engine 10 is a water cooled type that causes cooling water tocirculate inside a water jacket (not shown), and is connected to aradiator 20, described later.

[0055] A hydraulic pump 11 driven by the engine 10 is attached to a leftside of the engine 10. The hydraulic pump 11 provides hydraulic fluidtowards the control valve unit etc., described later. The hydraulic pump11 is connected to the control valve unit 12 and the hydraulic fluidreservoir 13 through hydraulic piping and a hydraulic hose (not shown)etc.

[0056] The control valve unit 12 is provided on the right front side ofthe swiveling frame 4. The control valve unit 12 has a number of controlvalves for controlling various actuators, and is attached onto beams 4Eand 4F. The control valve unit 12 is connected to the hydraulic pump 11,hydraulic fluid reservoir 13, oil cooler 21 etc.

[0057] The hydraulic fluid reservoir 13 is provided on the swivelingframe 4 at a rear side of the control valve unit 12. The hydraulic fluidreservoir 13 is attached on the beam 4F, and holds hydraulic fluid to besupplied to the hydraulic pump 11. The hydraulic fluid reservoir 13 isformed as an airtight box-shaped container using a front plate 13A, arear plate 13B, a left side plate 13C, a right side plate 13D, an upperplate 13E and a base plate 13F. The rear plate 13B cooperates with thecooling air duct 14, described later, to form one side surface defininga cooling air passage 15. The hydraulic fluid reservoir 13 is connectedto the control valve unit 12, hydraulic pump 11, oil cooler 21 etc.

[0058] The cooling air duct 14 is provided at a rear side of thehydraulic fluid reservoir 13 close to the hydraulic fluid reservoir 13.The cooling air duct 14 connects the sirocco fan 16, which will bedescribed later, with the radiator 20 and the oil cooler 21.

[0059] As shown in FIG. 5 and FIG. 6, the cooling air duct 14 comprisesa left side plate 14A extending from a left end of the rear plate 13B ofthe hydraulic fluid reservoir 13 to a rear side of the machine, a rightside plate 14B extending from a right end of the rear plate 13B to arear side, a frame plate-shaped rear plate 14C provided spanning rearends of each of the side plates 14A and 14B, an upper plate 14D providedoffset to the right side at upper parts of the right side plate 14B andthe rear plate 14C, and a base plate 14E provided at a lower side ofeach of the side plates 14A and 14B and the rear plate 14C. By attachingfront ends of each of the side plates 14A and 14B to the rear plate 13Bof the hydraulic fluid reservoir 13, the cooling air duct 14 formes thecooling air passage 15 together with the rear plate 13B.

[0060] The radiator 20, described later, and the sirocco fan 16, as acentrifugal fan above the oil cooler 21, are provided on the cooling airduct 14. The sirocco fan 16 is a centrifugal fan for blowing out airthat has been sucked along an axis of an impeller blade,circumferentially of the impeller blade, and is characterized in that itis small and has low noise compared to a propeller fan. The sirocco fan16 supplies cooling air through the cooling air duct 14 to the radiator20 and the oil cooler 21.

[0061] The sirocco fan 16 is formed in a substantially circular shapewith an axis in a lateral direction, and is mainly comprised of a fancasing 17 with external shape like a spiral increasing gradually inradius towards a discharge port 17A, a cylindrical impeller 18 which iscapable of rotation inside the fan casing 17 and has a plurality ofimpeller blades extending axially at an outer peripheral side, and adrive motor 19 which is attached to a motor bracket 4G of the swivelingframe 4 keeping a distance from the left side of the fan casing 17,being a hydraulic motor or electrical motor with an output shaft 19Aconnected to the impeller 18. The sirocco fan 16 has a discharge port17A of the fan casing 17 integrally attached to an upper left side ofthe cooling air duct 14.

[0062] By rotationally driving the impeller 18 with the drive motor 19,the sirocco fan 16 sucks air inside the impeller 18 from an intake port17B (only one side is shown in the drawing) provided opening to bothends in the axial direction of the fan casing 17 and discharges this airfrom the discharge port 17A of the fan casing 17 under centrifugalforce.

[0063] The radiator 20, as a heat exchanger, is attached to the rearplate 14C of the cooling air duct 14 below the sirocco fan 16. Theradiator 20 cools cooling water of the engine 10 using cooling air fromthe sirocco fan 16. The radiator 20 is connected to a water jacket ofthe engine 10 through a hose (not shown). The axis of the sirocco fan 16does not strictly need to be in the lateral direction, and can also bein the longitudinal direction or inclined slightly upwards or downwards.

[0064] The oil cooler 21, as a heat exchanger, is attached to the frontsurface of the radiator 20, and is positioned inside the cooling airduct 14. The oil cooler 21 uses the cooling air from the sirocco fan 16to cool hydraulic fluid returned to the hydraulic fluid reservoir 13from the control valve unit 12. The oil cooler 21 is connected to thecontrol valve unit 12 and the hydraulic fluid reservoir 13.

[0065] A partition plate 22 is provided on the swiveling frame 4, aroundthe sirocco fan 16. The partition plate 22 partitions the intake side ofthe sirocco fan 16, namely the intake port 17B of the fan casing 17,from the exhaust side of the radiator 20 and the oil cooler 21 and theengine 10. For this reason, the partition plate 22 is provided furtherup than the upper surface of the radiator 20, and enclosing the rear andleft sides of the fan casing 17 of the sirocco fan 16. Specifically, thepartition plate 22 substantially comprises a lateral plate 22A arrangedat a rear side of the fan casing 17 and extending to the left and right,and a longitudinal plate 22B arranged to the left side of the fan casing17 and extending from the lateral plate 22A to the front.

[0066] In this way, the partition plate 22 increases the coolingefficiency of the radiator 20 by sucking only externally cooled air fromthe breather 6D provided in the external cover 6 into the sirocco fan16.

[0067] Reference numeral 23 represents a canopy for covering above thedriver's seat 7 upon which an operator sits. (See FIG. 1)

[0068] Operation of the hydraulic excavator of this embodiment havingthe above-described structure will now be described.

[0069] An operator sits in the driver's seat 7 and causes the lowertraveling body 1 to travel by operating the travel lever 8. When theworking levers 9 are operated, the working unit 3 is made to move up anddown and the upper swiveling body 2 is made to swivel, making it ispossible to perform excavation operations.

[0070] When traveling or carrying out excavation operations as describedabove, cooling water for the engine 10 is cooled by the radiator 20 andthe hydraulic fluid is cooled by the oil cooler 21.

[0071] That is, the drive motor 19 of the sirocco fan 16 is driven tocause rotation of the impeller 18. In this way, inflowing external airis sucked into the impeller 18 from the breather 6D prepared in theright cover 6A of the external cover 6 and cooling air is expelled intothe cooling air duct 14 from the discharge port 17A of the fan casing17. Cooling air that has been expelled inside the cooling air duct 14 issupplied to the radiator 20 and the oil cooler 21 through the coolingair passage 15, and cooling water and hydraulic fluid are cooled by theradiator 20 and the oil cooler 21, respectively.

[0072] Since the cooling air passage 15 is defined by the cooling airduct 14 and the rear plate 13B of the hydraulic fluid reservoir 13,cooling air flowing through the cooling air passage 15 comes intocontact with the rear plate 13B of the hydraulic fluid reservoir 13.Consequently, it is possible to release heat of the hydraulic fluidstored in the hydraulic fluid reservoir 13 into the cooling air flowingthrough the cooling air passage 15 using the rear plate 13B, so that thehydraulic fluid stored in the hydraulic fluid reservoir 13 can becooled. Cooling air that has become heated up by passing through theradiator 20 and the oil cooler 21 is discharged to the rear, deflectedalong the covers 6A and 6B and an inner surface of the counterweight 5to the engine side on the left, and discharged to the outside from abreather 4H opening to the base plate 4 a of the swiveling frame 4 at alower side of the engine 10. The partition plate 22 partitions theintake side (intake port 17B) of the sirocco fan 16 from the exhaustside of the radiator 20 and the oil cooler 21, and from the engine 10.Cooling air that has passed through the radiator 20 and become heated,and air that has become heated due to heat from the engine 10, areprevented from flowing into the sirocco fan 16 again. As a result, thesirocco fan 16 can suck in only cool air sucked in from the breather 6D.

[0073] A description will now be given of carrying out inspection andmaintenance operations of the sirocco fan 16.

[0074] The right cover 6A of the external cover 6 is opened. The siroccofan 16 is arranged above the radiator 20 etc., in other words, it isarranged at a position where it is easy for an operator to reach in withtheir hand well within the field of view. Accordingly, the operator cansimply and visually inspect the impeller 18 and drive motor 19 etc. ofthe sirocco fan 16, and it is also possible to efficiently carry outmaintenance operations such as cleaning and servicing operations due tofaults etc. in a posture that is not uncomfortable.

[0075] In this way, according to the first embodiment, since the siroccofan 16 is provided as a cooling fan inside the engine compartment 100,it is possible to reduce rotation noise of the fan 16. Since the coolingair sucked in by the sirocco fan is fed to the oil cooler 21 and theradiator 20 and then discharged from a lower side of the engine 10, itis possible to feed low temperature air to the oil cooler 21 and theradiator 20, and it is thus possible to improve the cooling efficiencyof these heat exchangers. As a result, it is not necessary to increasethe size of the sirocco fan 16 and the radiator 20, thus the structuralsize of the engine compartment 100 can be reduced. It is also notnecessary to increase the rotational speed of the fan 16, making itpossible to prevent the rotational noise of the fan 16 becoming worse.

[0076] The sirocco fan 16 is arranged above the radiator 20 and the oilcooler 21, in other words the sirocco fan 16 is arranged at a positionclose to the operator. As a result, it is easy to carry out inspectionoperations and maintenance operations for the sirocco fan 16, thusoperability is improved. Since the sirocco fan 16, the radiator 20 andthe oil cooler 21 are arranged above or below each other, it is possibleto make the longitudinal dimensions of these parts smaller and to makethe upper swiveling body 2 smaller.

[0077] Since the cooling air duct 14 is defined by the rear plate 13B ofthe hydraulic fluid reservoir 13 together with the cooling air passage15, it is also possible to cool the hydraulic fluid stored inside thehydraulic fluid reservoir 13 using the rear plate 13B. Accordingly theefficiency of cooling the hydraulic fluid can be improved.

[0078] Because the rear plate 13B of the hydraulic fluid reservoir 13 isused as part of the cooling air duct 14, it is possible to reduce thenumber of components of the cooling air duct 14, making it possible toimprove ease of assembly and to reduce manufacturing costs etc.

[0079] Since the intake side of the sirocco fan 16 is partitioned offfrom the exhaust side of the radiator 20 and the oil cooler 21, and theengine 10 with the partition plate 22, it is possible to prevent coolingair that has become heated by passing through the radiator 20 etc. andair that has become heated by heat from the engine 10 from being suckedback into the sirocco fan 16. Therefore, because the sirocco fan 16 cansupply cool air sucked in from the breather 6D to the radiator 20 ascooling air, it is possible to efficiently cool the engine cooling waterand the hydraulic oil. Accordingly, reliability can be improved.

[0080] By providing the breather 6D at a high position of the rightcover 6A, it is possible to suppress the invasion of dust etc.Accordingly, lowering efficiency of cooling the radiator 20 etc., can besuppressed and simplification of cleaning operations etc., can beachieved.

[0081] The structure is such that the hydraulic pump 11 is arrangedoffset to the right side of the swiveling frame 4, the sirocco fan 16 isseparated from the engine 10, and the radiator 20, the oil cooler 21,the sirocco fan 16, the hydraulic fluid reservoir 13 and the controlvalve unit 12 are arranged offset to the right side of the swivelingframe 4 together with the hydraulic pump 11. Consequently, it ispossible to reduce the length of lines (not shown) for respectivelyconnecting the hydraulic pump 11 and the hydraulic fluid reservoir 13,the hydraulic pump 11 and the control valve unit 12, the control valveunit 12 and the oil cooler 21, the oil cooler 21 and the hydraulic fluidreservoir 13, and the control valve unit 12 and the hydraulic fluidreservoir 13.

[0082] As a result, it is possible to simplify handling at the time ofconnecting each of the lines to improve operability. It is possible toarrange the lines at a position separated from the driver's seat 7, andit is possible to provide a comfortable working environment bysuppressing pulsating emission noise from hydraulic piping around thedriver's seat 7. It is possible to widen a space around the driver'sseat 7, and this point also adds to improvement in the workingenvironment.

[0083] Because the sirocco fan 16 is separated from the engine 10 anddriven by the motor 19, the sirocco fan 16, radiator 20 and oil cooler21 can be arranged offset to the right side of the swiveling frame 4.Therefore, the hydraulic pump 11 provided on the engine 10 can be madecentral, and it is possible to arrange the sirocco fan 16, the radiator20 and the oil cooler 21 in a free relationship.

[0084] It is therefore possible to increase the degree of freedom of thearrangement relationship between the hydraulic pump 11, the radiator 20the oil cooler 21 and the sirocco fan 16. It is possible to arrangethese components efficiently on the upper turntable 2, and it ispossible to reduce the size of the upper swiveling body 2. The upperswiveling body 2 is capable of making small turns, and is suitable foruse in a mini excavator.

[0085] Since the axis of the sirocco fan 16 is provided in the lateraldirection, cooling air expelled from the sirocco fan 16 passes throughthe oil cooler 21 and the radiator 20 and is then deflected to the sideof the engine 10. This means that when providing arrangement space forthe sirocco fan 16 at the right side of the driver's seat 7, it ispossible to efficiently arrange the sirocco fan 16, as well as toprovide the breather 6D separated from the engine 10 and to suppress theoutward flow of engine noise from the engine. Cooling air that has beenguided to the engine 10 side is discharged from the breather 4H providedat the lower side of the engine 10 to the outside, which makes itpossible to reduce noise.

[0086] Second Embodiment

[0087] A second embodiment of a construction machine of the presentinvention will now be described with reference to FIG. 7 and FIG. 8.

[0088] The second embodiment is characterized in that the hydraulicfluid reservoir has a side surface forming the cooling air passage as aninclined surface inclining in a direction towards the heat exchangerside, wherein heat dissipating fins are provided projecting from theside surface defining a cooling air passage for the hydraulic fuel tank.With the second embodiment, the same reference numerals are used forstructural elements that are the same as those in the first embodimentdescribed above, and description of those parts will be omitted.

[0089] As shown in FIG. 7 and FIG. 8, the hydraulic fluid reservoir 31of the second embodiment is formed as a box-like container tightlyclosed by a front plate 31A, a rear plate 31B, a left side plate 31C, aright side plate 31D an upper plate 31E and a base plate 31F. A lowerportion of the rear plate 31B, that is below the central part in theupward and downward direction of the rear plate 31B forms an inclinedsurface 31G inclined towards the radiator 20, and the side plates 31Cand 31D are formed with the undersides widening out corresponding to theinclined surface 31G.

[0090] A cooling air duct 32 is provided at behind and adjoining therear side of the hydraulic fluid reservoir 31. The cooling air duct 32is formed from a left side plate 32A, a right side plate 32B, a rearplate 32C, an upper plate 32D and a base plate 32E, and the side plates32A and 32B are individually formed with their undersides inclined alongthe inclined surface 31G of the hydraulic fluid reservoir 31.

[0091] The cooling air duct 32 defines a cooling air passage 33 togetherwith the rear plate 31B by attaching a front end section of each of theside plates 32A and 32B to the rear plate 31B (inclined surface 31G) ofthe hydraulic fluid reservoir 31.

[0092] A sirocco fan 34 constituting a centrifugal fan of the secondembodiment is provided on the cooling air duct 32 above the radiator 20and the oil cooler 21. The sirocco fan 34 is comprised of a casing 35,an impeller 36 and a drive motor 37, similarly to the sirocco fan 16 ofthe first embodiment.

[0093] A plurality of heat dissipating fins 38, . . . , are provided onthe rear plate 31B of the hydraulic fluid reservoir 31. Each heatdissipating fin 38 efficiently releases heat of the hydraulic fluidinside the hydraulic fluid reservoir 31 into cooling air flowing throughthe cooling air passage 33. Each cooling fin 38 is provided on theinclined surface 31G extending in upward and downward directionsdefining the flow through direction of the cooling air and arrayed inthe lateral direction.

[0094] Substantially the same effects as those of the previouslydescribed first embodiment can also be obtained with the secondembodiment having this type of structure.

[0095] Further, according to the second embodiment, since the inclinedsurface 31G inclined towards the radiator 20 is formed on the rear plate31B of the hydraulic fluid reservoir 31, it is possible to guide coolingair towards the radiator 20 etc., so that efficiency of cooling thecooling water and the hydraulic fluid can be improved. Since the coolingair collides actively with the inclined surface 31G of the hydraulicfluid reservoir 31, it is also possible to efficiently cool hydraulicfluid inside the hydraulic fluid reservoir 31 using this inclinedsurface 31G. Since the inclined surface 31G enlarges the volume of thehydraulic fluid reservoir 31, it is also possible to prolong the timebetween hydraulic fluid replacement, and to reduce the size of thehydraulic fluid reservoir 31.

[0096] Since the plurality of heat dissipating fins 38 protrudingoutwards are provided on the rear plate 31B of the hydraulic fluidreservoir 31 and are positioned on the inclined surface 31G, it ispossible to enlarge the surface area of the rear plate 31B and todramatically improve the efficiency of cooling the hydraulic fluid.

[0097] Third Embodiment

[0098] A third embodiment of a construction machine of the presentinvention will now be described with reference to FIG. 9.

[0099] The third embodiment is characterized in that the hydraulic fluidreservoir and the cooling air duct are provided in separate bodies. Withthe third embodiment, the same reference numerals are used forstructural elements that are the same as those in the first embodimentdescribed above, and description of those parts will be omitted.

[0100] The cooling air duct 41 of the third embodiment is providedadjacent to a rear side of the hydraulic fluid reservoir 13, and thereis a slight gap between the cooling air duct 41 and the hydraulic fluidreservoir 13. Here, the cooling air duct 41 comprises a front plate 41Afacing the rear plate 13B of the hydraulic fluid reservoir 13 with aslight gap between the front plate 41A and the rear plate 13B, a leftside plate (not shown) extending from a left end of the front plate 41Atowards the rear of the swiveling frame, a right side plate extendingfrom a right side of the front plate 41A to the rear, a frame-shapedrear plate 41C provided spanning the rear ends of the right side plate41B and left side plate, an upper plate 41D provided offset to the rightside at upper sections of the front plate 41A, the right side plate 41B,and the rear plate 41C, and abase plate 41E provided at the bottoms ofthe front plate 41A, the right side plate 41B and the rear plate 41C. Acooling passage (not shown) is defined inside the cooling air duct 41,enclosed by the front plate 41A, the right side plate 41B and the rearplate 41C.

[0101] According to the third embodiment configured in this way, sincethe hydraulic fluid reservoir 13 and the cooling air duct 41 areprovided separately, it is possible to prevent vibration interferencedue to differences in vibration frequency between the two. Since thecooling air duct 41 is adjacent to the hydraulic fluid reservoir 13 witha slight gap, it is also possible to transfer heat of the hydraulicfluid inside the hydraulic fluid reservoir 13 to the cooling air duct41, and to release the heat into the cooling air.

[0102] The first embodiment was described giving an example for the casewhere the oil cooler 21 was provided at a front side of the radiator 20.However, the present invention is not thus limited, and it is alsopossible, for example, to have a structure where the oil cooler 21 isprovided at a rear side of the radiator 20. It is also possible tosimilarly apply this structure to other embodiments.

[0103] The first embodiment was described giving an example for the casewhere the drive motor 19 of the sirocco fan 16 was attached to the motorbracket 4G extending from the swiveling frame 4. However, the presentinvention is not thus limiting, and it is also possible to have astructure, for example, where the drive motor 19 is attached to the fancasing 17 via a bracket or the like. It is also possible to similarlyapply this structure to other embodiments.

[0104] With the first embodiment, the sirocco fan 16 was described ashaving an impeller 18 rotationally driven by the drive motor 19.However, the present invention is not thus limiting, and it is alsopossible to have a structure where, for example, the impeller 18 isconnected to an output shaft side of the engine 10 and rotationallydriven by the engine 10. It is also possible to similarly apply thisstructure to other embodiments.

[0105] With the first embodiment, description was given with an examplewhere a sirocco fan 16 was applied as a centrifugal fan. However, thepresent invention is not thus limited and it is also possible, forexample, to apply a centrifugal fan constituted by various types ofmulti-blade fan, multi-layer disk fan etc.

[0106] Fourth Embodiment

[0107] A fourth embodiment of a construction machine of the presentinvention will now be described with reference to FIG. 10-FIG. 16.

[0108]FIG. 10 is a front elevation of a hydraulic excavator of thefourth embodiment, and FIG. 11 is a plan view of this constructionmachine. As shown in FIG. 10 and FIG. 11, the hydraulic excavatorcomprises a traveling body 51, a swiveling body 2 that is provided onthe traveling body 51 and is capable of swiveling, an operator's seatsection 53 provided offset to the left side of a frame (swiveling frame62) of the swiveling body 2, and an operating section 54 made up of aboom 54 a movably attached to a right side of the swiveling frame 62, anarm 54 b and a bucket 54 c. An engine unit 55 and a counterweight 56 arearranged behind the operator's seat section 53.

[0109]FIG. 12 is a cross sectional drawing of the engine unit 55 in awidthwise direction of the machine (looking from the rear of themachine), FIG. 13 is a cross section along line XIII-XIII of FIG. 12(looking from the left of the machine), and FIG. 14 is a cross sectionalong line XIV-XIV of FIG. 12 (looking from above the machine). Anengine compartment 60 sealed by a cover 61 is formed behind theoperator's seat section 53, and an engine 63 is mounted on the swivelingframe 62 substantially in the center of the engine compartment 60.

[0110] As shown in FIG. 12, an air intake port 61 a and an air exhaustport 61 b are respectively formed in the left and right covers 61, andan air exhaust port 62 a is formed in the swiveling frame 62 beneath theengine 63. As will be described later, cooling air passes through theinside of the engine compartment 60 via these openings 61 a, 61 b and 62a. A partition plate 64 having a substantially L-shaped cross section isprovided extending in the longitudinal direction of the machine, at theleft of the engine 63. A lower surface of the partition plate 64 isfixed to the swiveling frame 62, a front end surface of the partitionplate 64 is fixed to a bulkhead 65 between the operator's seat section53 and the engine compartment, and a rear end surface of the partitionplate 64 is fixed to the counterweight 56.

[0111] As shown in a perspective view of FIG. 15, a duct 66 having ascroll section 66 a and a straight section 66 b connecting to the scrollsection 66 a is arranged to the left of the partition plate 64 in avertical direction of the machine, and the scroll section 66 a is fixedto the swiveling frame 62 and the partition plate 64. An intake port 66c for sucking in cooling air is formed in a front section and a rearsection of the scroll section 66 a, and a blowout opening 66 d forblowing out cooling air is formed in a right end section of the straightsection 66 b. As shown in FIGS. 12-14, a sirocco fan 67 having arotational shaft in the longitudinal direction of the machine is housedin an inner side of the scroll section 66 a. A plurality of stays 68(four in the drawing) are fixed to the rear surface of the scrollsection 66 a, and a hydraulic motor 69 is attached to the stays 68. Anoutput shaft of the hydraulic motor 69 is linked to the rotational shaftof the sirocco fan 67 through the intake port 66 c.

[0112] A radiator 70 is attached to the blowout opening 66 d above thesirocco fan 67 in a vertical direction so as to completely cover theblowout opening 66 d, and a lower end of the radiator 70 is fixed to anupper surface of the partition plate 64. A oil cooler 71 is arranged tothe left of the radiator 70 and substantially parallel to the radiator70, and the oil cooler 71 is fixed to the radiator 70 through a bracket71 a. A partition plate 72 is provided between an upper end section andfront and rear end sections of the radiator 70 in a machine longitudinaldirection, and the cover 61 and the bulkhead 65, and the enginecompartment 60 is divided into left and right portions (respectivelycalled a low temperature chamber 60A and a high temperature chamber 60B)with this partition plate 72 and the partition plate 64 and the duct 66.The low temperature chamber 60A and the high temperature chamber 60B arelinked through the intake port 66 c, duct 66 and blowout opening 66 d.

[0113] A hydraulic pump 73 driven by the engine 63 is provided to theright of the engine 63. The hydraulic motor 69 is driven by dischargedhydraulic fluid from the hydraulic pump 73, and the sirocco fan 67rotates. An intake pipe 74 is connected to the engine 63, an air cleaner75 is provided mid-way along the intake pipe 74, and a tip end sectionof the intake pipe 74 penetrates through the partition plate 72 andreaches the low temperature chamber 60A. A silencer 76 is arranged abovethe hydraulic pump 73, and a tip end of an exhaust pipe 77 connected tothe silencer 76 penetrates through the counterweight 56 and projects outto the rear of the machine. Hoses 78 and 79, for passing cooling water,are connected to the radiator 70. Although not illustrated, hoses forpassing hydraulic fluid are also connected to the oil cooler.

[0114] Next, operation of the construction machine of the fourthembodiment will be described.

[0115] If the sirocco fan 67 is rotated by rotation of the hydraulicmotor 69, cooling air at substantially atmospheric temperature flows infrom the air intake port 61 a of the left side cover 61 to the inside ofthe low temperature chamber 60A. This cooling air is sucked into theduct 66 from the intake port 66 c as shown by the arrow in FIG. 12.Sucked in air changes direction along the duct 66, passes sequentiallythrough the oil cooler 71 and the radiator 70, and performs heatexchange with hydraulic fluid inside the oil cooler 71 and cooling waterinside the radiator 70. Air passing through the duct 66 is lowtemperature, and is passing at a high speed since the passage area isrestricted by the duct 66. As a result, it is possible to efficientlycool the oil cooler 71 and the radiator 70. Cooling air that has risenin temperature due to heat exchange is fed from the blowout opening 66 dto the high temperature chamber 60B, passes around the engine 63 andhydraulic pump 73 etc. to cool the surfaces of these components, andthen some of the air is discharged from the air exhaust port 62 a to theoutside of the chamber while the remaining air is discharged from theair exhaust port 61 b.

[0116] After air in the low temperature chamber 60A has been suckedinside the intake pipe 74 and filtered by the air cleaner 75, it flowsinto cylinders of the engine 63. This inflowing air is compressed in thecylinders, then mixed with fuel for explosive combustion, followed bysound damping by the silencer 76 before being discharge to the rear ofthe machine through the exhaust pipe 77. Energy generated at this timeis conveyed to a crankshaft, and the crankshaft is driven.

[0117] With the fourth embodiment thus configured, the sirocco fan 67 isprovided as a cooling fan inside the engine compartment 60, and coolingair sucked in by the sirocco fan 67 is blown around the engine 63 andthe hydraulic pump 73 after being blown to the oil cooler 71 and theradiator 70, which means that it is possible to reduce rotational noiseof the fan 67, as well as to blow low temperature air to the oil cooler71 and the radiator 70 and improve the cooling efficiency of these heatexchangers. As a result, there is no need to increase the size of thefan 67 and the radiator 70, and it is possible to make the enginecompartment 60 small in size. There is also no need to increase therotational speed of the fan 67, and it is possible to preventdegradation in rotational noise of the fan 67. The rotational shaft ofthe sirocco fan 67 is arranged in the horizontal direction, with the oilcooler 71 and the radiator 70 provided above the rotational shaft, andcooling air from the sirocco fan 67 being blown to the oil cooler 71 andradiator 70 through the duct 66, which means that space efficiencyinside the engine compartment 60 is improved.

[0118] Since the engine compartment 60 is divided into the left andright portions with the partition plates 64 and 72, the partition plates64 and 72 act as heat shielding plates making it possible to suppresstemperature rise of the low temperature chamber 60A due to radiation(radiated heat etc.) from the engine 63. As a result, the temperature ofthe cooling air is dramatically lowered, and cooling efficiency isimproved. Because the sirocco fan 67, oil cooler 71 and radiator 70 arearranged behind the operator's seat section 53 and the engine 63 isarranged to the right of the radiator 70, that is, since the operator'sseat section 53 comes into contact with the low temperature chamber 60Amore often through the bulkhead 65, rise in temperature of theoperator's seat section 53 can be suppressed, which is obviously morecomfortable. It is also possible to arrange the partition plate 72 tothe right so that the rear surface of the operator's seat section 53comes into contact with the low temperature chamber 60A even more often(72 a in FIG. 14). Since a tip end of the intake pipe 74 is arranged inthe low temperature chamber 60A, air at substantially the sametemperature as the outside atmosphere is guided into the cylinders ofthe engine 63, and combustion efficiency is improved.

[0119] If it is desired to make the cooling efficiency of the radiator70 higher than that of the oil cooler 71, then it is possible, as shownin FIG. 16, to arrange the radiator 70 further upstream than the oilcooler 71, that is, to the left of the oil cooler 71. In this way, lowertemperature air is blown to the radiator 70 and cooling efficiency isimproved.

[0120] Fifth Embodiment

[0121] A fifth embodiment of a construction machine of the presentinvention will now be described with reference to FIG. 17.

[0122]FIG. 17 is a longitudinal cross section of an engine unit 55 ofthe fifth embodiment. Points that are the same as in FIG. 12 have thesame reference numerals, and the following description will focus onpoints of difference. The fifth embodiment is different from the fourthembodiment in the arrangement of the oil cooler 71. As shown in FIG. 17,the oil cooler 71 is arranged substantially horizontally to the left ofthe radiator 70, and is supported from the radiator 70 through a bracket81 at one end of the oil cooler 71 and an elongated support bracket 82at the other end. In this way, the oil cooler 71 is arranged at a placewhere a passage area is smaller than the vent section (blowout opening66 d) of the duct 66, and is arranged substantially vertically withrespect to the passage inside the duct 66, namely vertically withrespect to flow of cooling air.

[0123] By arranging the oil cooler 71 in this way, cooling air passessubstantially horizontally between fins of the oil cooler 71 and airresistance is made small. Also, cooling air flows in uniformly over theentire oil cooler 71 and the hydraulic oil is uniformly cooled. Sincethe oil cooler 71 is arranged at a location where the passage area issmall, the amount of cooling air that passes per unit area of the oilcooler 71 increases, and it is possible to make the oil cooler 71 smallin size. With respect to a limit that does not obstruct flow of coolingwater from the upper tank to the lower tank of the radiator 70, it isalso possible to provide the radiator 70 in an inclined manner, and itis therefore also possible to arrange the radiator 70 vertically withrespect to the passage at a place where passage area inside the duct 66is small.

[0124] Sixth Embodiment

[0125] A sixth embodiment of a construction machine of the presentinvention will now be described with reference to FIG. 18 and FIG. 19.

[0126]FIG. 18 is a cross section in the longitudinal direction of themachine of an engine unit 55 of the sixth embodiment, and FIG. 19 is across section along line XIX-XIX of FIG. 18. Points that are the same asthose in FIG. 12 and FIG. 14 have the same reference numerals, and thefollowing description will focus on points of difference. The sixthembodiment is different from the fourth embodiment in the arrangement ofthe sirocco fan 67. Compared to the fourth embodiment where therotational shaft of the sirocco fan 67 is arranged in the horizontaldirection, with the sixth embodiment the fan is arranged vertically, asdescribed in the following.

[0127] As shown in FIG. 18 and FIG. 19, a base platform 91 is fixed tothe left of the engine compartment 60 on an upper surface of theswiveling frame 62, and a duct 93 is supported on an upper surface ofthe base platform 91 through a stay 92. The duct 93 is made up of asubstantially cylindrical cylinder section 93 a, and an extensionsection 93 b opening out in a horn shape from a peripheral surface ofthe cylindrical section 93 a to the right. Openings 93 c arerespectively formed in upper and lower surfaces of the cylinder section93 a, and a discharge opening 93 d is formed in a right end section ofthe extension section 93 b. A hydraulic motor 69 is attached to the baseplatform 91, a sirocco fan 67 having a rotation shaft in the verticaldirection is housed in the cylinder section 93 a, and an output shaft ofthe hydraulic motor 69 is coupled to the rotation shaft of the siroccofan 67 through an intake port. The radiator 70 is attached to adischarge opening 93 d, and the oil cooler 71 is fixed to the left ofthe radiator 70. A lower part of the radiator 70 is supported in anupper end of a flat plate-shaped partition plate 94.

[0128] With this type of structure, cooling air flowing into the enginecompartment 60 due to rotation of the sirocco fan 67 flows into the duct93 through intake port 93 c. This inflowing air passes through the oilcooler 71 and the radiator 70 and is discharged from the dischargeopening 93 d, passes around the hydraulic pump 73 and is exhausted fromthe air exhaust ports 61 b and 62 a. In this way, low temperaturecooling air passes through the oil cooler 71 and the radiator 70, andcooling efficiency is improved.

[0129] Since the upstream side of the flow of cooling air (lowtemperature chamber 60A) is arranged at a rear surface of the operator'sseat section 53, rise in temperature of the operator's seat section 53is suppressed. Because the rotational shaft of the sirocco fan 67 isprovided in a vertical direction and the radiator 70 is arranged to theright of the sirocco fan 67, a space is formed beneath the radiator 70and it is possible to extend the radiator 70 downwards as shown by thetwo-dot chain line in FIG. 18. By doing this, the heat dissipating areaof the radiator 70 is increased to improve cooling efficiency, and it ispossible to reduce the rotational speed of the fan in proportion to thisincreased cooling efficiency to reduce the fan noise. Air resistance isslight because the oil cooler 71 and the radiator 70 are arrangedvertically with respect to the flow of cooling air.

[0130] Seventh Embodiment

[0131] A seventh embodiment of the present invention will now bedescribed with reference to FIG. 20.

[0132]FIG. 20 is a cross section of an engine unit 55 of the seventhembodiment in a widthwise direction of the machine. Points that are thesame as in FIG. 12 have the same reference numerals, and the followingdescription will focus on points of difference. As shown in FIG. 20, astraightening vane 101 for directing cooling air that has passed throughthe radiator 70 in a specified direction (sloping downwards in thedrawing) is provided on a right side of the radiator 70.

[0133] In this way, cooling air that has passed through the oil cooler71 is not discharged in that direction but is discharged towards a lowersection of the engine 63 making it possible to efficiently cool an oilpan 63 a etc, in the engine lower section. Noise radiated from theengine 63 by the straightening vane 101 is reflected, which means thatit is possible to reduce noise.

[0134] In the fourth to seventh embodiments, it is also possible for thearrangement of the engine 63 and the sirocco fan 67, oil cooler 71 andradiator 70 to be reversed laterally.

[0135] With the above described embodiments, description has been givenby giving an example of a swing type hydraulic excavator having anoperating unit 3, 54 that is attached to a front side of the upperswiveling body 2, 52 and that is capable of swinging in the left andright directions, but the present invention is not thus limited. Forexample, it is also possible to apply the present invention to an offsettype hydraulic excavator that has an operating unit arm and bucketmoving in parallel in the left and right directions. It is also possibleto apply the present invention to a general hydraulic excavator that isnot provided with a swing mechanism or offset mechanism.

[0136] With the above-described embodiments, descriptions have beengiven of cases applying both a radiator 20, 70 and an oil cooler 21, 71as heat exchangers. However, the present invention is not thus limited,and it is also possible, for example, to apply to a structure with onlyone of either the radiator 20, 70 or the oil cooler 21, 71. It is alsopossible to similarly apply other heat exchangers (for example, acondenser or intercooler) besides the radiator 20, 70 and the oil cooler21, 71.

[0137] With the above described embodiments, descriptions have beengiven using examples of the case applied to a hydraulic excavatorprovided with a canopy 23 covering the upper side of the driver's seat7, but the present invention is not thus limited and can also be appliedto a hydraulic excavator provided with a cab box for covering around thedriver's seat 7.

INDUSTRIAL APPLICABILITY

[0138] Descriptions have been given above with a tracked hydraulicexcavator, particularly a mini excavator, as an example of aconstruction machine. However, the present invention can also besimilarly applied to other construction machines such as medium andlarge sized hydraulic excavators, wheel type hydraulic excavators,hydraulic cranes, wheel loaders, bulldozers, etc.

1. A construction machine comprising, in a compartment formed by acover, an engine, a centrifugal fan, and a heat exchanger for exchangingheat between cooling air blown by the centrifugal fan and a specifiedmedium, wherein; the centrifugal fan and the heat exchanger are arrangedon an upstream side of the engine with respect to flow of cooling air,so that cooling air sucked in by the centrifugal fan is led to theengine side after passing through the heat exchangers.
 2. Theconstruction machine according to claim 1, wherein: an intake side ofthe centrifugal fan is partitioned off from an exhaust side of the heatexchanger and the engine.
 3. The construction machine according to claim1 or claim 2, further comprising: an operator's seat section that isoffset to one side in a widthwise direction of the machine, wherein; theengine is provided behind the operator's seat section, and thecentrifugal fan is arranged to the opposite side of the engine withreference to the widthwise direction of the machine.
 4. The constructionmachine according to claim 3, wherein: a rotational shaft of thecentrifugal fan is arranged substantially horizontally, and thecentrifugal fan is arranged above the heat exchanger, with a duct fordirecting cooling air from the centrifugal fan to the heat exchangers.5. The construction machine according to claim 3, wherein: thecentrifugal fan is arranged to an upper part of the compartment, and acooling air intake port is provided at an upper part of the cover. 6.The construction machine according to in any one of claim 3 to claim 5,wherein: a rotational shaft of the centrifugal fan is providedsubstantially in a widthwise direction of the machine.
 7. Theconstruction machine according to claim 6, wherein: an exhaust port forthe cooling air is provided below the engine.
 8. The constructionmachine according to any one of claim 3 to claim 7, wherein: a hydraulicpump driven by the engine is arranged at a centrifugal fan side of thecompartment.
 9. The construction machine according to any one of claim 3to claim 8, wherein: at least one of a hydraulic fluid reservoir forstoring hydraulic fluid, and a control valve for controlling flow ofhydraulic fluid from the hydraulic pump to an actuator, is arranged at acentrifugal fan side of the compartment.
 10. The construction machineaccording to claim 9, further comprising: a duct for guiding cooling airfrom the centrifugal fan to the heat exchanger, wherein the duct isarranged adjacent to the hydraulic fluid reservoir.
 11. The constructionmachine disclosed in claim 1 or claim 2, wherein: the heat exchanger isarranged behind an operator's seat section, and the engine is arrangedat a side of the heat exchangers side with reference to a widthwisedirection of the machine.
 12. The construction machine according to anyone of claim 1 to claim 3 and claim 11, wherein: a rotational shaft ofthe centrifugal fan is arranged substantially horizontally, and the heatexchanger is arranged above the centrifugal fan, with a duct fordirecting cooling air from the centrifugal fan to the heat exchanger.13. The construction machine according to any one of claims 1 to 3 andclaim 11, wherein: a rotational shaft of the centrifugal fan is arrangedsubstantially vertically with respect to a horizon, and the heatexchanger is arranged to a side of the centrifugal fan, with a duct forguiding cooling air from the centrifugal fan to the heat exchanger. 14.The construction machine according to any one of claims 1 to 3 andclaims 11 to 13, wherein: the heat exchanger is arranged substantiallyvertically with respect to flow of cooling air blown from thecentrifugal fan.
 15. The construction machine according to claim 12 orclaim 13, wherein: the heat exchanger includes an oil cooler and aradiator, the radiator is arranged in an outlet of a duct passage thatis formed by the duct, and the oil cooler is arranged substantiallyvertically with respect to the duct passage at a specified location ofthe duct passage having a smaller passage area than the outlet of theduct passage.
 16. The construction machine according to any one ofclaims 1 to 3 and claims 11 to 15, wherein: a straightening vane isprovided directly downstream of the heat exchanger with respect to theflow of cooling air, to change a flow of cooling air that has passedthrough the heat exchanger to a specified direction.
 17. Theconstruction machine according to any one of claims 1 to 16, wherein:the construction machine is a mini excavator.